The word “telemetry” generally refers to communications systems that make measurements at remote or inaccessible points, and transmit these measurements to receiving equipment where they are monitored, recorded, and displayed. Telemetric systems typically include one or more measuring/transmitting instruments, a medium of transmission, a receiver, and recording and/or display equipment. The measuring/transmitting instrument is usually a transducer, which converts physical stimuli into electrical signals.
One type of existing telemetry system is an underwater acoustic telemetry system, which may be used to determine the position of a submersible vehicle relative to an acoustic network. Such a system typically includes an acoustic sensor array positioned outside of a submersible vehicle, such as a submarine, and a plurality of outboard electronic (OBE) “bottles”. The OBE bottles are electronic subsystems packaged in pressure insensitive containers positioned outside of the submersible vehicle. Each OBE bottle typically receives and processes acoustic signals from multiple acoustic sensors in the acoustic sensor array. Each OBE bottle is typically linked to an inboard electronic subsystem via a duplex fiber optic link.
Current conventional duplex fiber optic telemetry links are inadequate for future large bandwidth acoustic arrays. Hull penetrations must be provided for a pair of fiber optic cables for each OBE bottle. Hull penetrations are expensive and generally undesirable. In addition, having complete optical transmission and receiving capabilities in each OBE bottle increases outboard power dissipation.
It is anticipated that larger arrays will be needed in future telemetric applications, including more OBE bottles with higher bandwidth. Expanding existing telemetry systems, such as the system summarized above, results in additional problems. Adding OBE bottles requires additional undesirable hull penetrations and results in even greater outboard power dissipation.
In addition, use of the existing Transparent Asynchronous Transmitter-Receiver Interface (TAXI) protocol for conventional telemetry systems appears to be near an end. TAXI is an older protocol that does not work well for large sensor arrays. It appears unlikely that vendors will continue to produce TAXI chipsets.
It would be desirable to provide a high bandwidth telemetry system at a low cost, with less complexity, fewer hull penetrations, less power consumption, and better reliability than existing systems, and that is extendible to large acoustic arrays.